This is a 16 weeks trial in which 120 T2DM patients will be screened with the aim to recruit 60 T2DM patients with vitamin D deficiency or insufficiency. Out of these 60 patients , 30 patients will be started on vitamin D supplementation and 30 patients will be given a matched placebo. Endothelial function (EF) will be checked before and after supplementation to see a change in EF.